Kevin Andrews says he would challenge Malcolm Turnbull for prime ministership under right circumstances

Dumped Liberal MP Kevin Andrews has revealed he is prepared to challenge Malcolm Turnbull for the prime ministership.

The veteran Victorian conservative and key ally of former prime minister Tony Abbott made the comments in an interview with his local paper, The Manningham Leader.

He said he had never "set out to be prime minister" but would challenge for the top job if he felt the time was right.

"It has never been my burning ambition to be the leader of the party, but if circumstances arose which they did in both of those instances where I thought there should be a change or a contest, I am prepared to do it," Mr Andrews said.

Kevin Andrews is an ally of Tony Abbott, with both key members of the Liberal right-wing. (AAP)

Bad blood exists between the prime minister and the Menzies MP, Malcom Turnbull having immediately dumped Mr Andrews from the Defence portfolio after taking over from Tony Abbott last September.

Mr Andrews unsuccessfully challenged Mr Turnbull for the Liberal leadership in 2009, a contest eventually won by Tony Abbott.

Mr Andrews, who was first elected to parliament in 1991 and was a minister in the Howard Government, also explained why he challenged deputy leader Julie Bishop during the September spill.

"There wasn't anything particularly negative about Julie, but she had been deputy leader under Brendan (Nelson), Malcolm, and Tony, and I thought, 'well, there hadn’t really been a contest for the deputy leadership'," he said.

Malcolm Turnbull's popularity has dipped after a strong start in the top job.

"I made that decision sort of spur of the moment because it just came up, so I thought there should be a contest, people should be able to decide who they want."

Mr Andrews lost the deputy ballot 30 votes to 70.

The admission will give further headaches for Malcolm Turnbull, who has suffered declining polls and a series of policy setbacks since broaching the now-ditched idea of raising the GST earlier this year.

He is struggling to control scorned former prime minister Tony Abbott and a Liberal right-wing distrustful of his progressive views, particularly on gay marriage and climate change, on top of an impending election campaign.